feat(aio): add initial doc viewer

with lots of fixes from Igor and Ward <3

angular.io/src/app/app.component.ts

@@ -1,10 +1,11 @@
 import { Component } from '@angular/core';
-
+import { NavEngine } from './nav-engine/nav-engine';
 @Component({
-  selector: 'app-shell',
+  selector: 'aio-shell',
   templateUrl: './app.component.html',
   styleUrls: ['./app.component.scss']
 })
 export class AppComponent {
   title = 'app works!';
+  constructor(public navEngine: NavEngine) {}
 }